230 DIAMONDS. 



were erupted with a mud volcano, together with all kindvS of d6bris 

 eroded from the adjacent rocks. The direction of flow is seen in the 

 upturned edges of some of the strata of shale in the walls, although I 

 was unable at great depths to see any upturning in most parts of the 

 walls of the De Beers mine. 



Let me again refer you to the section through the Kimberley miue. 

 There are many such pipes iu the immediate neighborhood. It may be 

 that each volcanic pipe is the vent for its own special laboratory — a 

 laboratory buried at vastly greater depths than we have reached or 

 are likely to reach — where the temperature is comparable with that 

 of the electric furnace, where the pressure is fiercer than in our puny 

 laboratories and the melting point higher, where no oxygen is present, 

 and where masses of carbon-saturated iron have taken centuries, per- 

 haps thousands of years, to cool to the solidifying point. Such being 

 the conditions, the wonder is, not that diamonds are found as big as 

 one's fist, but that they are not found as big as one's head. The chem- 

 ist arduously manufactures infinitesimal diamonds, valueless as orna- 

 mental gems; but nature, with unlimited temperature, inconceivable 

 pressure, and gigantic material, to say nothing of measureless time, 

 produces without stint the dazzling, radiant, beautiful crystals I am 

 enabled to show you to night. 



The ferric origin of the diamond is corroborated in many ways. The 

 country round Kimberley is remarkable for its ferruginous character, 

 and iron saturated soil is popularly regarded as one of the indicaticms 

 of the near presence of diamonds. Certain artificial diamonds present 

 the appearance of an elongated drop. From Kimberley I have with me 

 diamonds which have exactly the appearance of drops of liquid sep- 

 arated in a pasty condition and crystallized on cooling. At Kimberley, 

 and in other parts of the world, diamonds have been found with little 

 appearance of crystallization, but with rounded forms similar to those 

 which a liquid might assume if kept in the midst of another liquid 

 with which it would not mix. Other drops of liquid carbon retained 

 above their melting point for suflQcient time would coalesce with adja- 

 cent drops, and on slow cooling would separate in the form of large, 

 perfect crystals. Two drops, joining after incipient crystallization, 

 would assume the not uncommon form of interpenetrating twin Crystals. 

 Illustrations of these forms from Kimberley are here to-night. Other 

 modified circumstances would produce diamonds presenting a confused 

 mass of borty crystals, rounded and amorphous masses, or a hard, 

 black form of carbonado. 



Again, diamond crystals are almost invariably perfect on all sides. 

 They show no irregular side or face by which they were attached to a 

 support, as do artificial crystals of chemical salts ; another proof that 

 the aiamond must have crystallized from a dense liquid. 



When raised the diamond is in a state of enormous strain, as I have 

 already shown by means of polarized light. Some diamonds exhibit 



